


Taboo

by ChromeHoplite, gxlden



Series: Sebaciel Dialogue Prompts [7]
Category: Kuroshitsuji | Black Butler
Genre: College student Sebastian, High School Senior Ciel, M/M, Sibling Incest
Language: English
Status: Completed
Published: 2018-07-17
Updated: 2018-07-17
Packaged: 2019-06-12 00:45:32
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 4,052
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15328008
Author URL: https://archiveofourown.org/users/ChromeHoplite/pseuds/ChromeHoplite, https://archiveofourown.org/users/gxlden/pseuds/gxlden
Summary: Ciel visits his dear, dear brother at college [and shows him how much he misses him].





	Taboo

**Author's Note:**

> This is our last drabble for our dialogue prompt challenge, specifically for: _You were supposed to stop me_
> 
> We've been trying to write out of our comfort zone with some of these drabbles, and this one was definitely way out there for us. We hope you enjoy it nonetheless.

Why did Sebastian have to go to such a big school? 

It had taken Ciel twice as long as he’d expected to find his half-brother’s dorm on the massive, populated campus. Twice, he had walked into the wrong building and climbed two flights of stairs before realizing he was not in the right place and had to walk back out, relocate his car in one of the crowded lots, and try again. 

Finally, he found his way to the co-ed building and made his way to the boy’s floor, and now stood before Sebastian’s door. He hadn’t seen him since he’d come home for Christmas break, and Ciel couldn’t deny he was excited to see him again. They had a lot to catch up on, so he took a deep breath and pounded on the door. 

Sebastian came down the hall with a towel slung low around his waist, hair damp and dripping and a bag of toiletries under his arm. He caught sight of the shaggy mop of hair standing outside his room and had to do a double-take; Ciel wasn’t supposed to come visit until tomorrow. 

He watched as two girls walked by his unassuming younger brother, turning their heads appreciatively. One of them cat-called and Sebastian wasn’t surprised that Ciel didn’t even notice; the teenager had no clue how beautiful he was. 

He stood behind his oblivious brother, leaning in to whisper, “This asshole’s never home,” in a low baritone. 

Warmth trickled down Ciel’s neck at the sound of the honeyed voice, along with a cold drop of water that gave him chills. 

“You’re telling me,” he scoffed. “Never there when you need him.” Smugly, he turned on his heel to face Sebastian, unperturbed by his indecent state; after so many years, Ciel had almost grown desensitized to the sight of Sebastian’s body. _Almost._ There was a twitch in his fingers, a repressed urge to reach out and touch the small jagged scar on his chest that Ciel had given him when they were young. He was mad at Sebastian, and so twelve-year-old Ciel had crashed into him on his dirt bike, sending Sebastian to the hospital for stitches. He wanted to know what the pale strip of skin felt like; he wondered if Sebastian ever noticed it in the mirror and thought of him. 

“I can see why you’d want to stay away,” Ciel said, pushing his hands in his pockets. “It’s hot as balls in this building.” 

The corner of Sebastian’s mouth twitched and he pulled his brother in for a hug, rubbing Ciel’s face against his exposed skin. “How do you know this isn’t sweat, baby brother?” 

At first, Ciel embraced the hug, patting Sebastian jovially on his still-slick back before pretending to pull away in disgust. “Come on,” he said, “I’m starving. I’ve been on the road for hours, let’s go do something.” 

“Fine, lemme get some clothes on first,” Sebastian replied, moving Ciel aside to get to his room. He crossed the threshold and side-stepped the piles of books, clothes and beer cans scattered on the floor. His room was a disaster, and he’d planned on cleaning it up tomorrow morning before Ciel got here. He cleared a spot for his brother to sit on his bed, and turned down the picture of himself and an attractive redhead on his desk, hoping his brother hadn’t seen it, and feeling a patch of heat spread across his face as he did so. “So, where do you wanna go eat?” he asked, turning away from Ciel and towards his dresser to fish out some clothes. He got into his underwear with his towel still on, then let it fall as soon as he was somewhat decent. 

“Your room is a mess, dude,” Ciel laughed as he plopped down on the bed. Sebastian had always been so neat and organized back home; his childhood bedroom was immaculate. Ciel wondered what else had changed about him since starting college. “I’m in your hands,” he said, trying not to stare as Sebastian wiggled into a pair of pants. “Whatever’s good around here… I don’t care. I’m just happy to see you, you know?” 

Sebastian grinned; he was happy too. He meant to ruffle Ciel's hair affectionately the way he used to, but when his hand found the soft, slate locks, his fingers lingered too long in them and he was seized by the desire to pull on them a little, to make a fist in them just to see his brother’s eyes close and his teeth press down against his bottom lip. 

But he didn't. He let go immediately when Ciel looked up at him from under his lashes. 

“I missed you,” Ciel admitted in a low murmur. There were a few stubborn drops of water still clinging to the ends of Sebastian’s hair. Ciel watched them fall onto his bare shoulder as he admitted, “I honestly couldn’t wait to see you… I came up a day early so we could hang out more. I know you’re busy, so I hope you’re not mad at me.” Bashfully he extended his hand, hoping Sebastian would take it, or pull him in for another hug, tell him he missed him too. 

Sebastian stared at the extended hand between them; he never noticed how dainty Ciel’s hands were. His fingers were long and slender, with something graceful about them. There was tensing in his abdominal muscles and in the pit of his stomach as he pictured Ciel’s hands dragging along his chest, blunt nails leaving pink scratches as they went further down, or else digging into his back. 

Genetics! Ciel took after his mother, she’d been playing piano since before Sebastian’s father had married her. 

He smacked Ciel’s hand in a sort of sideways hi-five, “I missed you too, little buddy.” The words sounded all wrong in his head. Ciel wasn’t so little anymore, and as a senior in high school he was a man now, wasn’t he? “You know I’d have driven up anytime you wanted me. We didn’t have to wait three months.” 

Ciel shook his head slightly, balled his hands into fists on his legs. “But I always want you,” he murmured. “Ever since you left home… I don’t know what to do with myself. Dad and Rachel are different when you’re gone. I’m different…” 

For months, Ciel had been denying himself, punishing himself for the way he thought about his half-brother. He was a sicko, a pervert for wanting to touch him, kiss him, love him as more than just a brother. Dirty thoughts would pervade his head throughout the day, followed by a sick, guilty feeling. It made it hard to focus in class or study at home. More than once he had gotten slammed on the soccer field because he was daydreaming of Sebastian coming back to watch one of his games. 

He had to open up, get it off his chest, get it into the open. 

Sebastian sat on the bed next to Ciel, more than a little confused himself. Not only was he baffled by his brother’s tone, and the longing underlying his words, but he couldn’t make sense of his own sudden urge to pull Ciel closer, to touch him and comfort him the way he did with Mey-Rin when she was in one of her moods. His fingers twitched with need at his sides; how wrong would it be for him to tuck a stray lock of Ciel’s hair behind his ear, or to trace his pouted bottom lip with his thumb? 

Wrong. Really, really wrong. 

He drew in a deep, calming breath, and so as to not seem out of sorts to his brother, put his hand on his knee and asked, “Hey, are you okay? Is there something going on at home I should know about? Is dad giving you a hard time about liking boys again?” 

_Not all boys_ , Ciel thought, _just the one_... 

It was obvious he tended under Sebastian’s touch; he refused to look in his eye as he spoke. “I miss you, Sebastian,” his voice cracked he looked up, flicking his hair out of his eyes with a shake of his head, “so much…” 

And then something overcame him, something Ciel wouldn’t be able to explain in a hundred years. All of his fears, his worries and insecurities blew away with the warm breeze from outside. He put his hand on top of Sebastian’s, leaned over and craned his head up as far as he could. Their lips touched, Sebastian’s half open, maybe in protest, and Ciel felt like he was soaring, his stomach dropping deep and fast. 

Sebastian’s breath hitched and he was frozen in place, eyes wide. Ciel was hesitant in his kiss, his lips warm and seeking like he was asking permission. And Sebastian wanted to give it to him. He was curious, his own mouth eager to know Ciel in ways he didn’t yet. In ways he _shouldn’t_ know him. He pulled back, forehead resting against his brother’s, “What’re you doing, Ciel?” he exhaled. 

“I’m sorry,” Ciel’s eyes were glossy — with desire, with ashamed tears, it was hard to tell. He hadn’t let go of Sebastian’s hand. “I’m so sorry…. I’ve wanted to do that for so long. I couldn't wait any longer. Fuck, I’m so disgusting… You’re my brother. You were supposed to stop me...” Ciel suddenly shot up from the bed and walked to the furthest corner of the room, pounding himself in the head. “What the hell was I thinking… I should just go.”

_Shit_. Sebastian hadn’t meant to do that. He just needed to be certain that was what Ciel wanted. He crossed the length of the room in four long strides and cornered his brother, grabbing both his small hands and holding them in a one-handed grip to his bare chest to keep the boy from hitting himself. When Ciel looked as if he was going to protest, Sebastian silenced him with two fingers to his trembling lips and kissed his soft cheek, his furrowed brow, then lingered at the corner of his mouth. “Don’t go… please… just don’t tell Dad.” 

Tears threatened to break free as Ciel shook his head. The same blood ran through their veins; their father’s, and he would disown them both if her ever found out. And that fear made the kiss that much more divine; Ciel’s lips were still tingling. He wanted more. 

“I won’t tell if you won’t tell,” Ciel whispered tentatively. 

Sebastian released Ciel’s hands, reached over to his door and twisted the deadbolt handle to a locked position. Ciel had always been a spoiled little thing and always got what he wanted. Maybe it was because he’d always been stunning, or because the sound of his voice was sweet and irresistible. Sebastian had always been a sucker for his big blue eyes, especially when they held a hint supplication and desire. But this time the desire was not for a toy, or to borrow a too-big sweater or for his big brother to drive him around. This time those eyes were heavy-lidded with wistful carnality. He didn’t know how far Ciel wanted to take this, all he knew was that he’d never been able to deny his brother anything in the past and he wasn’t going to start now. 

Sebastian slipped his hand round Ciel’s petite waist and drew him closer until they were flush against one another. He was certain his brother could feel the banging of his heart inside his chest. It was wrong. It was wrong. And as he pressed his lips to the side of Ciel’s neck and mouthed the graceful column with a moan and a sigh, he didn’t care anymore. 

Ciel had always been envious of Sebastian’s looks; hated the ease with which his older brother managed to get dates, wished he had the self-confidence that Sebastian had. Boldly, but a little sloppily, he grabbed Sebastian’s chin and brought his face to his, pressing their lips together once more. He moaned into the kiss, letting his body melt against Sebastian’s, closer than he had ever been to his brother. 

Sebastian parted his brother’s lips with his tongue, smoothing over the bottom one with a swipe and plunging into the heat of his mouth to lick and tease the wet muscle inside. Ciel’s whimper and the inexperienced kiss of teeth caused Sebastian’s hands to drift unconsciously to the boy’s backside. He kneaded and groped and squeezed, clutching Ciel’s ass and hitching him up against the wall, perfect slender legs wrapping themselves around his waist. “Are you?” he panted, pulling away, “Have you ever…”

Color began to climb Ciel’s cheeks and he ducked his head, trying to hide his blush. He tugged nervously on a tendril of hair at the back of Sebastian’s neck. “No, I’ve never… I’ve never really been with anyone before,” he admitted, cursing himself. Was is that obvious? “I’m not as personable as you are, Seb,” he jabbed harmlessly. “Girls don’t throw themselves at my feet like they do to you… and definitely not any guys.” 

A renewed stab of guilt pierced the college student, and his hands stilled in their ministrations. It was bad enough Ciel was his brother, but a virgin as well? What kind of monster was he even contemplating claiming both? His touch became less fevered, a little more tender as he moved them to the bed and laid Ciel down on his side. He slipped in next to him, petting his face affectionately with the back of his hand, as his other tangled itself in the hem of Ciel’s shirt to restrain him from feeling the fevered skin underneath. “Are you sure about this?”

Ciel couldn’t bear to face his brother. The instant he admitted he was a virgin he could feel the mood shift, the intensity and passion leave the room, which left him embarrassed and deflated. The blush on his cheeks intensified and his face felt hot as he nodded shyly. “I’m sorry,” he choked out. “I didn’t want anyone but you… and I didn’t realize it for a while, and so I haven’t been with anyone, and it’s… I just want you so badly, Sebastian. It’s embarrassing. But I’ve never been more sure.”

Sebastian had done his due diligence and the longer he looked at Ciel, desperate on his bed, the more his considerate facade crumbled. “Alright, but you’ll have to tell me if it gets to be too much.” And with that, his lips were on Ciel again, mouth and chin, throat and chest as he dragged the collar forcefully down. His hands wandered under his shirt, felt warmth and goosebumps and ribs between his long fingers. “I want you too,” he said, words muffled against his brother’s skin. 

Already Sebastian’s touches were driving Ciel mad, whether the elder brother knew it or not. Ciel never thought it would actually happen. Sure, he had thought about it, pictured it, but now it was really happening; his smart, athletic, handsome older brother — the favorite son —was kissing him, pulling his shirt off over his head, touching him, looking at him like he was the most beautiful thing he had seen. 

Ciel fumbled with the zipper of Sebastian’s pants, too excited, so eager to please him. “Take them off,” he half-asked, half-ordered.

Sebastian complied, even went a step further and took off his underwear. He’d never seen this side of Ciel; gone was the shyness and uncertainty. This Ciel knew exactly what he wanted, and Sebastian couldn't have found that any more attractive if he’d tired. 

He wasted no time getting his brother naked, admired his lithe form, the slight definition of muscle under flawless, milky skin and the perfect pink of his jutting cock. When Ciel tried to sit up, Sebastian splayed his fingers over his chest and pushed him down against the pillow, then wrapped his hand around Ciel’s length. It was hard and hot, already pulsing and thrusting into his fist. He sat on his knees between Ciel’s thighs and spread them a bit wider as he jerked him off in slow, steady strokes. “Fuck Ciel, you’re gorgeous like this, you know? You gonna keep being quiet or you gonna tell me what you want?” 

“Shut up,” Ciel gasped, out of instinct. He could feel how hot his face was, his whole body in fact. It was all Sebastian’s fault. They’d seen each other naked before, but this was completely different. This was uncharted territory. He wasn’t used to feeling self-conscious in front of his brother. “Fuck, I don’t know,” Ciel moaned, sitting up on his elbows, at a loss as to what he wanted to do. “Use your mouth?” 

Sebastian’s cock throbbed between his legs, and as he leaned over Ciel’s, kissing the flushed tip and smearing the pearly fluid spilling from it with his lips, he fisted his hard on. With each sound Ciel made, Sebastian wanted more of him. He devoured him, licked him, took in the whole length, bobbed his head slowly at first, then with increasing fervour as Ciel grabbed his hair by the roots and pulled at it harshly. Sebastian hissed and moaned and his brother buried himself repeatedly in his mouth; it was difficult to believe he hadn’t done any of this before. He released Ciel, both of them panting and told him, “I’m gonna get you ready now, okay?” 

Sweat was dripping down the side of Ciel’s face and pooling in the concave angles of his chest as he heaved one breath after another, the air thick with the smell of Sebastian. “Okay,” he nodded. “Um… will it hurt?” He felt safe to ask as Sebastian got up and sought out a bottle of lube, resettling himself back between Ciel’s legs when he returned to the cramped twin XL mattress. Even though this was new and terrifying and totally unbelievable, it was still his big brother, and Ciel trusted him beyond a shadow of a doubt. 

“Maybe a little; I’ll be gentle.” Sebastian spilled lube over his fingers and rubbed them together to make sure they were well coated. He spread Ciel, pouring the warming fluid over the tight pucker between his ass cheeks and admired it a moment before pressing his finger to it. 

Ciel was holding his breath, wasn't looking at him or making a sound. Sebastian leaned over his brother, wrapping his free arm beneath him to hold him close. He kissed his neck, his face, his shoulder as he fingered him slow and deep, then squeezed in another. He didn't just want to prepare Ciel, he wanted to give him pleasure. So he rocked into him, praising him between kisses, “So beautiful, Ciel. So tight. So warm. You get me so hard. I've never been this hard for anyone before.”

Sebastian’s words helped distract Ciel from the burning stretch between his cheeks, otherwise he felt like he would tear in two. It did hurt, it was hot and uncomfortable, but Sebastian made him feel even hotter, and the feeling was starting to grow on him. 

“Fuck, Sebastian,” he said weakly, finally speaking up. His voice was raspy and he didn’t know what else to say. He really wanted to ask if Sebastian ever thought about him like this before, if he ever wanted to kiss him as badly as Ciel wanted to kiss and taste him. Instead he fumbled blindly between the two of them, one hand on his cock and the other on Sebastian’s, stroking and rubbing in jerky, uncoordinated movements. 

Sebastian groaned against his brother’s skin when he felt him clumsily groping their cocks. He sat back up, and with his other hand, wrapped it around Ciel’s, guiding and steadying it over their lengths. “Look at me when you do that,” he ordered hoarsely, finger fucking the smaller boy, twisting his wrist, curling his digits inside Ciel and finally rubbing the tight little bundle of nerves. 

“Ah! O-okay,” Ciel said with a shaky breath. “Whatever you say, Seb… that feels good.” The slick sounds of skin on skin rang in Ciel’s ears, made him blush. It was so dirty, so taboo. But it felt right, and he was sure Sebastian thought so too. 

“When… when are you gonna put it in me?” he asked sheepishly. He would make his innocence work in his favor, milk his inexperience for all it was worth, and let Sebastian deflower him, completely ruin him. He wouldn’t have it any other way. 

And Sebastian saw through his brother’s act. It didn’t matter, he would indulge him, he always did. He released their cocks, removed his fingers from inside Ciel and slathered his dick with more lube. He knew from experience that Ciel’s pain threshold was low, and while he didn’t want to hurt him unnecessarily, part of him also wanted to hear Ciel whine and hiss, see tears clinging to his long lashes as he squeezed his eyes shut. When his length glistened and dripped with slickness, he hitched Ciel’s legs up with ease, letting them sit at the crook of his elbows. “Are you ever going to grow out of being so demanding?” he teased with a smirk, and when the head of his cock was aligned with his brother’s stretched hole, he pushed in gently, one inch at a time until he bottomed out. 

Ciel didn’t answer -- he couldn’t, not when he was being stretched and filled by the most perfect person in the world. All he could manage was a whimper, a debasing moan as he reached desperately for Sebastian. His brother was tender, waiting for Ciel to adjust before slowly rolling his hips into him, caressing his legs and waist and chest and wherever else his hands could reach. 

“You can’t help it,” Ciel said suddenly, fisting his hair as his toes curled. Every now and again, Sebastian’s cock brushed something inside him that made him see stars. His head was spinning. “Even when we were kids, and I was a spoiled little brat… if I wanted something, you would get it for me. You’re a good big brother.” 

“And what is it you want now, Ciel?” Sebastian practically crooned, thrusting more insistently, fingers digging into his brother’s hips but slipping as sweat dewed the sensitive skin. Feeling his peak near, he folded Ciel under himself, held the back of his slender thighs and changed the rhythm of their fucking to something more aggressive, pumping his dick in and out of his greedy hole until the bed creaked beneath them. He watched Ciel’s face, pupils blows, lips trembling, body shivering and asked, “Want to come? Touch yourself, show me how you do it at home when you’re thinking of me.” 

“Yeah…” Ciel said shakily. His whole body was on fire, his ass burning, and he felt sticky and wet; Rachel had bought Sebastian the set of sheets before he left for college, and Ciel would be embarrassed beyond belief if he stained them. Sweat dripped into his eyes and he desperately tried to blink it away as he put his hand on his cock. 

The slow, tender pace he usually had at home didn’t seem to fit the situation; this was fast, and lustful -- years, maybe, of pent up feelings. So Ciel stroked himself with a frantic need, rough and desperate for release. He made an embarrassing sound as he came, spilling on his fingers and stomach and Sebastian’s chest. 

“Will you,” he gasped, “do it inside me?” 

It was too late to answer or give any thought to Ciel’s question; his brother’s strangled cry pushed him immediately over the edge. He slammed hard into Ciel twice and on the third time, swallowed a string of vulgar words and sounds as he crammed him full of his dick and filled him in jerky, uncoordinated movements. 

Sebastian’s eyes screwed closed as he lowered himself gently, elbows at either sides of Ciel’s head. He kissed him tenderly, told him he loved him and as he came down from his high and withdrew from Ciel, he sat at the edge of his bed with his head in his hands. 

“Don’t worry,” Ciel said, rolling gingerly onto his knees and resting a hand on his brother’s back, “I won’t tell Dad.”


End file.
